From: joe@strout.net   
      
   In article <44BCF84B.7338935F@nospam.com>,   
    Andrew Nowicki  wrote:   
      
   > Joe Strout wrote:   
   >   
   > > But airships (whether filled with hydrogen or helium) are.   
   > > Big ones can have a quite impressive lift capacity, too.   
   >   
   > The problem is how to bring the balloon or the airship   
   > back to the earth -- you would have to release lots of   
   > expensive hydrogen.   
      
   Why?  Normal airships don't release lifting gas; they compress it, by   
   inflating internal bladders with air.  I don't see why it should be any   
   different for this application.   
      
   > > Did you consider a power source on the ground beaming power   
   > > to the helicopters in the form of lasers or microwaves?   
   >   
   > Leik N. Myrabo experimented with this idea some 20 years ago.   
   > It works, and it is not very expensive. The microwave   
   > electronics would cost about $100 per 1kg of the rocket weight.   
   > (Batteries cost about $200 per 1kg of the rocket weight.)   
   > I did not mention microwaves because the safety concerns would   
   > drive up the cost.   
      
   But they reduce the logistical issues.  I wonder whether the safety   
   issues can be mitigated by careful selection of the wavelength used.   
      
   Best,   
   - Joe   
      
   --- SoupGate-Win32 v1.05   
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